RF Blocking Filter for Wireless Charging Coil Noise
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Solution Overview
Problem
Wireless charging of portable communication devices generates radio frequency noise that interferes with communication circuits and antennas, causing issues like decreased RF sensitivity and dropped calls.
Innovation Solution
Incorporating radio frequency blocking filters in both the wireless charger and the communication device to attenuate RF noise and harmonics, using printed wiring coils in a coplanar configuration for efficient electromagnetic induction, and optimizing filter circuits with capacitors and inductors to provide high attenuation at specific frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless charging is implemented using electromagnetic induction, then charging convenience and mobility are improved, but radio frequency noise is generated that interferes with communication circuits and antennas
Solution Approach 1:
The patent introduces RF blocking filters as intermediary components between the wireless charging coil and the communication circuits/antennas. These filters act as mediators that allow the wireless charging function to operate while blocking harmful RF noise from reaching the communication systems, thus resolving the contradiction between charging convenience and RF noise interference
Solution Approach 2:
The patent segments the wireless charging system into distinct functional blocks with separate filtering paths. By dividing the system into charging function blocks and communication function blocks with dedicated RF blocking filters for each, the patent enables independent optimization of each function while preventing mutual interference through structured separation
2Reliability
If RF blocking filters are added to reduce noise, then RF performance is improved, but device complexity increases
Solution Approach 1:
The patent applies RF blocking filters locally at specific points where RF noise generation or interference is most critical - namely at the charging coil output and at the input of communication circuits. This localized filtering approach provides effective RF noise suppression while minimizing the overall complexity increase by targeting only the most problematic areas rather than implementing system-wide complex filtering
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Significantly reduces radio frequency noise and harmonics during wireless charging, improving RF performance and preventing interference with communication signals, allowing for simultaneous use of wireless charging and communication without signal distortion.
Implementation Method 1
The alternating magnetic field produced by the transmitting coil inductively couples with a corresponding receiving coil in the cellular phone or other portable communication device, thereby producing a corresponding induced alternating current
Implementation Method 2
The source alternating current is passed through a radio frequency blocking filter to limit radio frequency noise
Data Source
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AI summary
Example embodiments are disclosed for limiting radio frequency noise created during wireless charging of rechargeable batteries in radio frequency communication devices. In an example embodiment, a power source circuit in a wireless charging device produces a source alternating current in a frequency range between 50 kHz and 20 MHz. The source alternating current is passed through a radio frequency blocking filter (110) to limit radio frequency noise. The filtered source alternating current is then driven through a transmitting coil (120) in the charging device. The alternating magnetic field produced by the transmitting coil (120) inductively couples with a proximately located receiving coil (220) in a radio frequency communication device, using contact-less electromagnetic induction. The radio frequency communication device may be a mobile communications device, FM radio, two-way radio, PDA, cell phone, laptop or palmtop computer, or the like. The alternating magnetic field produces a corresponding induced alternating current in a frequency range between 50 kHz and 20 MHz in the corresponding receiving coil (220) in the radio frequency communication device. The induced alternating current is passed through a second radio frequency blocking filter (210) that limits radio frequency noise that could otherwise be created by the rectifier and control circuits on communication device. The filtered induced alternating current is rectified to an appropriate DC charging voltage for the rechargeable battery. In this manner, radio frequency noise is limited during wireless charging of rechargeable batteries in radio frequency communication devices, to reduce the effects of such noise on the communication circuits and the RF antenna of the communication device. Moreover, RF performance is improved by limiting spurious emissions, RF noise, and harmonics generated in rectifier and control circuits. Antenna performance is improved by floating the charger coils in the RF frequencies of the communication device.